Device to Device (D2D) communication refers to a technology through which terminals can communicate directly without the need of forwarding by the network. Because forwarding by base station is not required, a lot of mobile network resources can be saved and the network capacity can be further enhanced.
At the same time, the main working modes of D2D include: point-to-point communication and broadcast communication; currently, 3GPP research topics are dominated by the broadcast communication. The point-to-point communication of D2D is similar to traditional cellular communication. The broadcast communication is composed of one transmitting node and a plurality of receiving nodes, and more than one forwarding may exist during communication. Since multiple receiving nodes are involved in the broadcast communication and channels of the transmitting nodes are independent of each other, maximum power is generally used for transmitting in order to ensure broadcast coverage.